Re: Page fault handling in vpagetable area clarification

From:

Aggelos Economopoulos <aoiko@xxxxxxxxxxxxxx>

Date:

Sat, 10 Feb 2007 18:32:14 +0200

On Saturday 10 February 2007 00:11, Matthew Dillon wrote:
[...]
> In anycase, I think doing a technical article is a great idea and please
> feel free to ask as many questions as you like, either in private mail
> or on this kernel list. I would love to get more information about the
> VKERNEL's design out to the wider world :-)
I'll keep the technical questions public so that web searches can find them.
In vm_fault_object(), fs.prot gets downgraded unconditionally if this is a
VM_MAPTYPE_VPAGETABLE entry. But if this was a write fault,
vm_fault_vpagetable() has already set VPTE_M (and if the vkernel clears it,
its pmap_clearbit() will invalidate the real kernel's pagetables). Why can't
the protection stay RW in this case?
Aggelos